1. Field of the Invention
The present invention relates to a method of forming a thin film, and more particularly to a plasma enhanced chemical vapor deposition method.
2. Description of the Related Art
A plasma enhanced chemical vapor deposition method is one of the most important techniques for forming a thin film in the semiconductor manufacturing processes. A thin film is often formed over a glass substrate by use of the plasma enhanced chemical vapor deposition method. The thin film is deposited over almost entirety of an upper surface of the glass substrate which is placed in a deposition chamber of a plasma enhanced chemical vapor deposition system. The deposition chamber has an inner wall and electrodes. The deposition may appear not only on the glass substrate but also on the inner wall of the deposition chamber and the electrodes in the deposition chamber.
As the thin deposited on the inner wall becomes thick, this may generate particles in the deposition chamber, wherein the particles may make a semiconductor device defective. In order to avoid this problem, it is necessary to carry out a plasma discharge process using NF3 gas or SF6 gas for removing the once deposited thin film from the inner wall of the deposition chamber.
The plasma discharge process may, however, cause unintended removals of alumina protection films which cover a surface of a substrate holder which is made of an aluminum-based material and also of an electrode surface. Aluminum is inferior in adhesion with the deposited thin film as compared to alumina film. The removals of the alumina protection films may generate particles in the deposition chamber, wherein the particles may make a semiconductor device defective.
For the above-described reasons, when the alumina protection film is etched from the surface of the substrate holder or the surface of the electrode, then the substrate holder or the electrode is removed from the deposition chamber for subsequently carrying out an alumite process to the substrate holder or the electrode in accordance with an anodic oxidation method, thereby forming the alumina protection film. This additional process is, of course, inconvenient and drops the manufacturing efficiency.
In the above circumstances, the development of a novel plasma enhanced chemical vapor deposition method free from the above problems is desirable.
Accordingly, it is an object of the present invention to provide a novel plasma enhanced chemical vapor deposition method free from the above problems.
It is a further object of the present invention to provide a novel plasma enhanced chemical vapor deposition method, wherein an alumina protection film is formed on a surface of either a substrate holder and an electrode in a deposition chamber of a plasma enhanced chemical vapor deposition system without, however, opening the deposition chamber.
It is another object of the present invention to provide a novel method of maintaining a plasma electrode and a substrate holder in a deposition chamber of a plasma enhanced chemical vapor deposition system free from the above problems.
It is a further object of the present invention to provide a novel method of maintaining a plasma electrode and a substrate holder in a deposition chamber of a plasma enhanced chemical vapor deposition system, wherein an alumina protection film is formed on a surface of either a substrate holder and an electrode in a deposition chamber of a plasma enhanced chemical vapor deposition system without, however, opening the deposition chamber.
The present invention provides a method of maintaining a plasma electrode and a substrate holder in a deposition chamber of a plasma enhanced chemical vapor deposition system. Each of the plasma electrode and the substrate holder comprises an aluminum-based material coated with an alumina protection film. The method comprises the steps of: after a plasma enhanced chemical vapor deposition process is carried out to a substrate, taking out the substrate from the deposition chamber; introducing a reaction gas into the deposition chamber; causing a reaction of the reaction gas for cleaning an inner wall of the deposition chamber; introducing an oxygen-containing gas into the deposition chamber; and generating an oxygen-containing gas plasma to form the alumina protection film on surfaces of the plasma electrode and the substrate holder.
The above and other objects, features and advantages of the present invention will be apparent from the following descriptions.